1. Field of the Invention
The present invention relates to an IC card and a manufacturing method thereof.
2. Description of the Prior Art
IC cards generally employ a structure in which the inner components, such as electric circuit boards having specific electronic parts and the like incorporated therein, are disposed in a resin frame of which the top and bottom surfaces are covered by a pair of metal panels.
The term "IC Card," as used herein, refers to a card-like or plate-like device which comprises electronic circuits including semiconductor circuits or electric circuits, and includes PC cards, modem cards, LAN cards, memory cards and electronic cards having the same basic arrangement as the above.
In one known IC card structure (hereinafter referred to as prior art structure 1), the resin frame constituting the exterior of the card has a structure split into upper and lower parts. Such a card is assembled by uniting the upper and lower frames with the upper and lower metal panels, respectively, in advance and by joining the upper and lower frames together by techniques such as ultrasonic welding.
As shown in FIGS. 20-23, an IC card 101 according to prior art structure 1 has a resin frame which is split into the upper and lower parts, and is thus comprised of an upper frame 102U and a lower frame 102L. The upper frame 102U and an upper metal panel 107 are united to form an upper package 109U, while the lower frame 102L and a lower metal panel 108 are united to form a lower package 109L. The frames 102U, 102L and the metal panels 107, 108 are respectively united by, for example, so-called panel-frame integral molding method when the resin frames 102U, 102L are molded.
A module 103 is formed by mounting a connector 106 to one end of an electric circuit board 104 having specific electronic parts and the like 105 incorporated therein, and the IC card 101 is subsequently assembled by interposing the module 103 between the upper package 109U and the lower package 109L and then by joining both the packages 109U, 109L together.
As is evident from FIGS. 22 and 23, a protrusion (weld) 102a for welding, having a section of a specific size and of a specific shape (e.g. a triangular shape), is formed on the joint surface of one of the upper and lower frames 102U, 102L, for example, continuously along the circumference of the frame 102L.
The upper and lower packages 109U, 109L are jointed together so that the protrusion 102a for welding comes into contact with the end surface of the upper frame 102U. The contact part is pressed from above and below and subjected to ultrasonic vibrations so that the protrusion 102a melts to join the upper and lower frames 102U, 102L together at their end surfaces.
In another known IC card structure (hereinafter referred to as prior art structure 2 ), the upper and lower metal panels are bonded to a unitary frame with adhesive sheets.
In an IC card 111 according to prior art structure 2, as shown in FIGS. 24-27 for example, a module 113 formed by mounting a connector 116 to one end of an electric circuit board 114 having specific electronic parts and the like 115 incorporated therein is incorporated into a unitary resin frame 112, and adhesive sheets 119U, 119L having adhesive applied to both the surfaces thereof are temporarily bonded to, for example, the upper and lower sides of the frame 112.
Upper and lower metal panels 117, 118 are then attached to the upper and lower sides of the frame 112, and the metal panels 117, 118 are bonded and fixed to the upper and lower sides of the frame 112 by heating under a predetermined temperature condition and by pressing from above and below, so that the IC card 111 is assembled.
In Japanese Patent Laid-Open Publication No. HEI 3-96396 (hereinafter referred to as prior art structure 3), as shown in FIGS. 28 and 29, IC cards 121, 131 are disclosed wherein metal panels 127, 128 and 137, 138 having their circumferential portions pressed into a predetermined shape are set in depressions 122b, 132b formed on a frame 122, 132. Projections 122a, 132a formed on the outside edge portions of the frame 122, 132 are softened by local heating and then press-molded from above with a die to embed and fix the circumferential portions of the metal panels 127, 128 and 137, 138.
In prior art structure 3, the circumferential portions of the metal panels 127, 128 and 137, 138 are provided with joint openings 127h, 128h and 137h, 138h for allowing resin, respectively.
In Japanese Patent Laid-Open Publication No. HEI 3-259364 (hereinafter referred to as prior art structure 4), as shown in FIG. 30, an IC card 141 is disclosed wherein metal panels 147, 148 are set in depressions 142b formed on a frame 142. Projections 142a formed on the outside edge portions of the frame 142 are pressed with a hot press 149 to embed and fix the circumferential portions of the metal panels 147, 148. In prior art structure 4, the outside surfaces of the end portions of the projections 142a are tapered to reduce the amount of softened resin softened during the press with the hot press 149.
As disclosed in, for example, Japanese Patent Laid-Open Publications No. HEI 3-45397, No. HEI 3-112689, or No. HEI 7-160837, another known IC card structure (hereinafter referred to as prior art structure 5) includes metal panels which are fixed to a frame by providing engaging portions or press-fit portions comprising hooks, tongues, or the like on the metal panels and by engaging those portions with the frame or pressing those portions into the frame, though the cards are not such that the metal panels are fixed by deforming a part of the resin frame by pressing.
The prior art structures mentioned above, respectively, have the following drawbacks:
In prior art structure 1, it is necessary to unite the metal panels 107, 108 and the resin frames 102U, 102L, respectively, for example, by the panel-frame integral molding method when the frames are molded. Therefore, it is expensive to provide the upper package 109U and the lower package 109L.
In prior art structure 2, bonding and fixing the metal panels 117, 118 to the frame 112 requires the adhesive sheets 119U, 119L in addition to the assemblies. Therefore, the cost increases because the number of components handled during the assembling process increases, and because an additional process step is required to temporarily bond the adhesive sheets 119U, 119L to, for example, the frame 112.
In the IC cards 121, 131 according to prior art structure 3, on the outside edge portions of the frame 122, 132 are formed the projections 122a, 132a which are softened, then pressed and deformed to embed and fix the circumferential portions of the metal panels 127, 128 and 137, 138. The projections 122a, 132a are pressed and deformed directly with the dies.
As a result, in order to sufficiently fix each metal panel 127, 128 and 137, 138 in this case, taking the edge portions on the left sides in FIGS. 28 and 29 as an example for explanation, the mode of deformation has to be controlled so that the projections 122a, 132a are inwardly deformed by the pressure exerted on the projections 122a, 132a in the direction illustrated as arrow F in the drawings. Also, the influence of the deformation of the projections 122a, 132a appears on the outer circumferential portions of the IC cards 121, 131, thus impairing their appearances.
In prior art structure 4, an unfavorable influence on the appearance of the IC card 141 occurs because the projections 142a are formed on the outside edge portions of the frame 142, and because the projections are pressed and deformed directly with the hot press 149.
In prior art structure 5, it is generally difficult to obtain a stable fixing force sufficient to withstand long-term use because the hooks, tongues, or the like provided on the metal panels are simply engaged with or pressed into the frame.
The present invention has been made considering the above problems, and is intended to provide an IC card and a manufacturing method thereof, wherein the upper and lower panel members are fixed to the resin frame in a way which provides high reliability, reduced manufacturing costs, and favorable appearance.